Electrically-heated tool.



, H- w. LEONARD. Patented July 5, l90l ELEGTBIGALLY HEATED TOOL.

. (Application flied Apr. 24, 1896.)

(no ludal.)

' UNITED STATES PATENT O EEICE.

HARRY WVARD LEONARD, OF EAST ORANGE, NEXV JERSEY.

ELECTRICALLY- HEATED TOOL.

SPECIFICATION formingpart of Letters Patent No. 678,410, dated July 16, 1901.

Application filed April 24-, 1896.

To all whom it Wuty concern.-

Be it known that I, HARRY WARD LEONARD, a citizen of the United States, residing in the borough of Manhattan, city and county of NewYork, State of New York, (formerly re,- siding at East Orange, in the county of Essex and State of New Jersey,) have invented a certain new and useful Improvement in Electrically-Heated Tools, of which the following is a specification.

My invention relates to apparatus in which electric energy isfconverted into heat-such as rheostats, electrically-heated tools, and electric heaters-and more particularly relates to apparatus intended to be operated at comparatively high temperaturessuch, for instance, as flat-irons; and it consists in so disposing the heating-conduetor that it is free to expand and contract without injurious mechanical strain and so that it is in contact only with a medium which does not cause any chemical depreciation of the heating-conductor,'said conductor being so arranged that a very long length may be placed in a comparatively small space.

Furthermore, my invention consists in distributing the heating-conductor within the flat-iron, so that the heat energy developed in the heated conductor will be uniformly dissipated and the maximum amount conducted to the working surface.

In carrying my invention into effect I employ an infusible insulating material, such as steatite, in solid form as a core or support for the heating-conductor. This material is given the desired shape by working it on a lathe or otherwise, the preferred form being cylindrical. WVhen the material is shaped into the desired form, I cut a Very fine screwthread upon its surface, into which a very fine heating-conductor is wound. The number of threads to the inch and the size of the conductor will vary according to the heat energy required.

A screw-thread on a cylindrical core provides a simple and rapid way of applying the heating-conductor to its support, and when a Very fine conductor is employed the same can be uniformly wound on the core without any difficulty whatever, which is a matter of considerable importance. I have found it extremely desirable to give the thread upon Serial 1%. 588,878. (No model.)

the core a solid clean smooth surface, and particularly the side Walls thereof, because the heating-conductor when placed therein will be free from depreciation by mechanical stress or chemical combination, and the conductor lying in the thread makes a very uniform and perfect contact with the surface, and the conductor itself is uniformly heated. The threads also prevent contact between the turns of the conductor, even though its expansion by heat causes it to rise somewhat from the bottom of the thread, in which case the conductor would adjust itself uniformly so as to make good contact along one of the side walls of the thread between the top and bottom of the thread. This constant uniform contact of the conductor with its support prevents the conductor from becoming overheated at different points, and thus saves the conductor from burning out.

The flat-iron is a solid casting having no joints in the metal which will retard the flux of heat from the heating-conductors to the working surface. This casting is provided with a number of cylindrical holes parallel to the longer axis of the iron, and in these holes I place the cores having the heatingconductors wound thereon. By providing several holes in one casting for the cores carrying the heating-conductors better conduction of heat to the working surface is obtained. These cores may be about threequarters of an inch in diameter. By employing four cores I may wind them to one standard and use four of them, whether for one hundred and twenty-five, two hundred and fifty, or five hundred volt circuits, by coupling them all in multiple or two in multiple series or all in series, respectively.

My invention is illustrated in the accompanying drawings, in which- Figure 1 is a plan View of a fiat-iron, the cores carrying the heating-coils and the leading-in wires being shown in dotted lines; Fig. 2, an end view of the fiat-iron with the end plate carrying the circuit-terminals and binding-posts removed; Fig. 3, a sectional view on the line m or of Fig. l; and Fig. 4, an enlarged view of a portion of one of the cores, with the heating-conductor and wrapping of insulation shown in section.

Referring to the drawings, A is the flatiron, having four cylindrical holes, into which are inserted the cores B, of insulating material, having the heating-conductor G wound thereoii. A layer D of insulation is placed between each core and the surrounding metal. This may be done by covering the cores after the conductors are wound thereon with any suitable material. A simple and effective way of doing this is to apply a wrapper of mica, or the cylindrical holes may be lined with insulation. a recess a, which is covered by a plate A, of

insulating material, carrying bindingposts a and a" for the circnit-wires. The object of the recess a is to leave ample room for the leading-in wires 0, which connect the heatingcoils with the circuit-terminals, and to guard against contact with the surrounding metal. These wires may be led directly to the bases of the binding-posts, but to avoid crossing of the wires and to facilitate the making of connections I employ two metal terminals 6 and 6 secured to the inner side of plate A and connected, respectively, with the binding-posts a and a The heating-coils, as shown in Fig. 1, are connected in multiple.

The leading-in wires 6 must be insulated, since they are liable to become short-circ'uited; but in practice these conductors become quite hot, and it is veryimportant to insulate them with a material which will withstand a high heat and not interfere with the flexibility of the conductors. I have found that disks, blocks, or beads e of solid refractory or infusible insulating material, with the wires threaded through them, give good re sults, because the disks or beads do not impair the flexibility of the wires and they are easily applied to the wires at the desired place.

What I claim is- 1. In an apparatus wherein electric energy is converted into heat, the combination of a cast-iron body or support, and several separable resistances carried thereby and arranged so that they lie in close proximity to the cast iron body or support practically throughout their length, whereby a large portion of the heat energy developed in said resistances under operative conditions will be rapidly transmitted to said cast-iron body or support.

is converted into heat, the combination of a cast-iron body or support, and several separable resistances mounted on separate supports carried by said cast-iron body or support and arranged so that the resistances lie in close proximity to the cast-ir0n body or support practically throughout their length, whereby a large portion of the heat energy developed in said resistances under operative conditions will be rapidly transmitted to said cast-iron body or support.

3. In an apparatus wherein electric energy is converted into heat, the combination of a cast-iron body or support provided with a se- The rear end of the iron has In an apparatus wherein electric energy ries of cylindrical holes, and a series of separate conductors wound upon cylindrical cores adapted to be inserted into the cylindrical holes, whereby the conductors will lie in close proximity to the cast-iron body or support practically throughout their length, and whereby a large portion of the heat energy developed in said conductors under operative conditions will be rapidly transmitted to said cast-iron body or support.

4E. In an apparatus wherein electric energy is converted into heat, the combination of a cast-iron body or support provided with a series of cylindrical holes, and a series of separate conductors wound upon cylindrical cores made of steatite adapted to be inserted into the cylindrical holes, whereby the conductors will lie in close proximity to the castiron body or support practically throughout their length, and whereby a large portion of the heat energy developed in said conductors under operative conditions will be rapidly transmitted to said cast-iron body or support.

5. In an apparatus wherein electric energy is converted into heat, the combination of a cast-iron body or support provided with a series of cylindrical holes, a series of separate conductors wound upon cylindrical cores adapted to be inserted into the cylindrical holes, whereby the conductors will lie in close proximity to the cast-iron 'body or support. practically throughout their length, and whereby a large portion of the heat energy developed in said conductors under operative conditions will be rapidly transmitted to said cast-iron body or support, circuit-terminals carried by the cast-iron body or support, and insulated conductors connecting said terminals with the separate conductors on the cores.

6. A fiat-iron having a series of cylindrical holes, and cores having heating-conductors wound thereon and adapted to be inserted in said holes, and whereby the heating-condnctors are held in close proximity to the surrounding metal of the flat-iron practically throughout their length, and whereby a large portion of the heat energy developed in said conductors under operative conditions will be rapidly transmitted to the surrounding metal.

7. A flat-iron having a series of cylindrical holes, and cores of insulating material having heating-conduetors wound thereon and adapted to be inserted in said holes, and whereby the heating-conductors are held in close proximity to the surrounding metal of the flatiron practically throughout their length, and whereby a large portion of the heat energy developed in said conductors under operative conditions will be rapidly transmitted to the surrounding metal, and a layer of insulation between the cores carrying the conductors and the surrounding metal. of the flat-iron.

8. A flat-iron having a series of cylindrical IIG holes,cores having heating-conductors wound thereon and adapted to be inserted in said holes, and whereby the heating-conductors are heldin close proximity to the surrounding metal of the fiat-iron practically throughout their length, and whereby a large portion of the heat energy developed in said conductors under operative conditions will be rapidly transmitted to the surrounding metal, a plate for covering the opening at one end of the iron through which the cores are inserted in the cylindrical holes, circuit terminals carried by said plate and to which the heatingconductors are connected, and binding-posts on said plate for the external circuit connections, substantially as set forth.

9. A flat-iron cast in one piece and having H. WARD LEONARD Witnesses:

EUGENE OoNRAN, CHARLES BECK, 

